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Improving the success rate of Yamadori

I have been using this technique now for over ten years and I have finally decided to share what I have learned. The technique is known as ‘sweating’ and is used extensively in arboretorial circles. I use for the following species: Cratageus, Prunus, and most of the Rosaceae family, do not use on evergreen species.

I collect trees with as much root as possible, but I have put roots on trees that have not had any.

” I have lots of question. Sorry i’m french, i speak bad english.
I want to do a yamadori of Ulmus campestris
– Can I do the yamadori for the month of March or april with black plastic bag? If yes, then I put the black bag in full sun outside, half shade, shade or in a cellar?
– Can i use this technical on ulmus?
– The ulmus that I want to take is in a stone wall, Can this technique work for an elm without rootlets?
Thank you man.”

I used your technical for two Ulmus this year and it’s 100% successfull.

But your technique has failed for a big oak and a maple of montpellier =( . When the new shoots reached 5cm, i remove from the bag and protect from cold and wind, mist spray daily and keep out of direct sunlight. But 2 mouth later the leaves of oak and maple have dried… When i scraped the bark, there wasn’t green, i remove trees from the pot and no roots have pushed…

Why do you think my tests are unsuccessfull ?

Should I put my trees in a transparent bag or a greenhouse after the black bag?

Thanx for writing about this great technique, I am using it second year now and it is working prefectly, I manage to put roots on a rootless yamadori hawthorn with trunk girth of about 15cm. Helped on many more trees too I believe and I put every yamadori in a bag since then. I am praising it everywhere I go with a reference to you and this article.
Only negative thing I noticed so far is mold buildig up on some trees, but it looks like it doesn´t come back after I brush it off with a toothbrush.
One question – at the moment I have a garden yamadori japanese maple collected a month ago, trunk diameter about 18cm – it is producing quite strong odour in the bag – is is ok to use this technique for it too? I am also worried about maple´s liability to catch various fungal diseases….which coul be aided by this wet environment…do my worries make sense?

Thanx for the responses Tony.
We have got few cold days in the last 2 weeks so thats why probably there was mold , bags didn´t get warm enough.
Today it ´s just 3°C again so I expect it to build up again.
As long as it don´t hurt the trees I don´t mind brushing it off.
Anyways, it´s like christmas for me everytime I open the bags and see buds appearíng all over the trunks on more and more trees now after a month in bags, even on a big ones with some 20cm diameter trunks that my local bonsaists would be preparing tree years for collection 🙂 Very handy technique.
All the best from your slovakian follower 🙂

hello Tony,
I’ve collected a Hawthorn and treated the way you advised: in a big black plastic bag, spraying daily. I’ve placed it in the livingroom, in front of the heater. Now, a month after digging, the tree has new shoots, lenght between 1 and 8 cm.
So now i think its time for point 16: When the new shoots reach 5cm or 2” remove from the bag and protect from cold and wind, mist spray daily and keep out of direct sunlight…. proctection from cold, does that mean: keep it frostfree, but place outside? Or what is the best i can do now? I think this is a tricky moment…
Many thanks!

Great tips! My trick is vitamin B-1. It reduces transplant shock which is generally about 2 weeks, but can be even less with B-1. I’ve seen new growth in a little over a week. We don’t typically have to worry about humidity domes where I live in Oregon.

Hi, great work Tony, I have a collected semi cascade Blackthorn, have a few questions… does the bag need to be air tight or should there be holes pricked in the bag?
I’m considering bagging the bottom half of my tree to gain some sacrifice branches and nebari…
Justin

Hi Tony
i dig up an old sea-buckthorn with deadwood and a hollow tree in february, and placed it in a container as you decribed here above. The three had hardly no roots. I places the tree inside the house with good light, in a big plastic box i made for the three. Every day i spray the tree, so the enviroment is always damp. within two weeks buds began to sprout. Now the the shoots are around 5 cm. Last week i remove the box, but the three was not happy with it: The leaves began to dry out. So now the plastic box is over it again. I give the tree superthrive for several times.
What is the best i can do now? Hope that you can give me some tips to give the tree alive and kickin

It’s all about heat and humidity… If the shoots are strong put the whole tree in a clear plastic bag. Make sure the new shoots do not touch the sides of the bag… Make a wire frame and put the bag over that… Seal the bottom… Spray regularly

Hi Tony,
Can I use this method of sweating on an old Azalea I collected from the garden of a house Demolition?
Also…is it a good idea to remove all the field soil and replace it with a pumice and sea soil mix or to leave some of the field soil close to the trunk and remove the rest in the second transplanting?

Thanks for publishing this method. A few of questions.
1. Can the trees be placed inside the house with central heating instead of outside in the sun?
2. Why is misting necessary? Surely if there’s water in the pot already and the bag is kept warm enough then it will keep very humid all by itself by evaporation. No water can leave the sealed bag.
3. Do you add mycorrhizal fungi / Q4 when potting or do you just rely on there being some left in the small amount of soil left on the roots?

Tony, I find this quite incredible and fascinating. Have you done an experiment to see a comparison of using a clear bag with partial sun vs. black bag and full sun? Is the time of year of significance?
I find the technique fascinating.

I tried this almost exact process last year based on rumors it was being done in Europe( probably you). I had similar success with a large old Ostrya (hop-Hornbeam). My soil mix was 1/2″ Perlite and pumice with 15% chopped sphagnum. It is exciting process to use with our hard budding horn-beams and hawthorns.